French lightweight solar panel manufacturer Heliup has partnered with Holcim’s Elevate brand to launch Solar Light TPO, a rooftop PV system that combines lightweight solar modules with a waterproofing membrane. The solution is designed for roofs with limited load-bearing capacity.
French lightweight PV module manufacturer Heliup has partnered with Elevate, a Holcim Group brand specializing in waterproofing and insulation, to launch Solar Light TPO, an offer combining Heliup’s lightweight Stykon PV modules with Holcim’s UltraPly TPO waterproofing membrane, available in thicknesses ranging from 1.5 mm to 2 mm.
Solar Light TPO weighs 7 kg/m², compared with 15 kg/m² to 20 kg/m² for conventional systems, including the waterproofing membrane. It uses a mounting method that requires no roof penetrations, additional rails, or ballast.
“This makes it possible to install PV systems on flat roofs that were previously difficult to equip, particularly on commercial, industrial and logistics buildings, as well as public facilities,” Jean-Luc Roudaut, director of new photovoltaic market development at Holcim, told pv magazine France.
Suitable for new buildings and roof renovations
The system can also accommodate different roof designs, including pitched roofs, sawtooth roofs with slopes of up to 100%, and curved surfaces. It is suitable for both new construction and roof waterproofing renovations.
The UltraPly TPO membrane is available in three thicknesses: 1.5 mm, 1.8 mm and 2 mm. The thickest option is particularly suitable for roofs requiring regular maintenance and servicing.
“Our profiles are highly complementary, allowing us to leverage multiple routes to market based on specific needs: a network of waterproofing contractors and project managers on Holcim’s side, and project owners, solar industry players and developers on Heliup’s side,” said Roudaut.
PV installation possible up to two years after waterproofing
Solar Light TPO has obtained an Enquête de Technique Nouvelle (ETN), a French technical assessment for innovative construction systems, and a Broof (t3) fire classification.
The system also meets French regulatory requirements for buildings open to the public (ERP) and facilities classified for environmental protection (ICPE).
“The advantage of the ETN is that it allows photovoltaic panels to be installed up to two years after the membrane is laid,” said Julien Gaume, technical director at Heliup. “This offers the flexibility to renovate the roof first and then add solar capacity later to comply with regulatory obligations.”
In March, Heliup raised €16 million ($17.9 million) to accelerate large-scale deployment of its lightweight PV technology.
Heliup said the funds will strengthen its commercial teams, expand production capacity at its French industrial site, prepare replicable industrial units, and continue technology development.
The company, based in Le Bourget-du-Lac in France’s Savoie region, operates a 4,000 m² factory in Le Cheylas, Isère, which has been operational since January 2025. The facility can produce up to 100 MW per year, which is equivalent to about 500,000 m² of panels.
Heliup launched a 10 MW pilot production line in 2023 under the France 2030 program and previously raised €10 million. In 2025, it expanded to industrial-scale production with support from the European Union’s Innovation Fund through the Solar HEliup Energy for Flat roofTop (SHEEFT) project.
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